The invention concerns a contact unit for a card-shaped carrier element of electronic components, especially in accordance with PCMCIA standards, comprising a plug-in or insertable card-shaped housing that comprises a base plate and a cover plate that is congruent thereto at least in the transverse direction, between which is formed a slot-like insertion channel that opens on one side of the housing for accommodating a chip-card, and that at the opposing side is provided a plug-in strip, and furthermore comprising arranged parallel to the insertion channel in the housing a printed circuit board that is connected electrically to the plug-in strip and that is provided on its surface with a contact field for contact with the chip-card.
Given the increasing miniaturization in the field of computer technology, electronic components are more and more frequently arranged on or in card-shaped carrier elements with a view toward variability and transportability. Frequently encountered are carrier elements in accordance with PCMCIA standards that are cards that comprise a standard-compliant matrix-like connector strip and can accommodate a great variety of electronic components, depending on application. For instance, such cards are employed as memory expansion cards, drive cards, modem cards, etc. The interface to a data processing system (e.g., a notebook computer) is created by means of the plug-in strip, which effects a mechanical and electrical contact with a PCMCIA slot in the data processing system.
Widely used are chip-cards that have integrated circuits and comprise flush contact fields arranged for contact with, e.g., correspondingly designed reading units. Known areas of application for this type of chip-cards are currently telephone cards, authorization cards, or what are known as "SmartCards".
Known in the current art are contact units that make it possible to connect a chip-card to a PCMCIA standard interface in a data processing system. The combination of a PCMCIA card and a chip-card contact unit that can be inserted into a corresponding modular insertion slot in a computer and then read is useful in a wide variety of applications (e.g., electronic banking, pay TV, authenticating access authorization to data networks, etc.). The disadvantage is that known chip-card readers of this type comprise an extension in the housing in the form of an enlarged insertion guide for the chip-card that extends beyond the insertion area of the modular insertion slot in the computer and that simultaneously provides a grip for the user. This means the readers are substantially longer than standard PCMCIA cards so that when in the operating position this extension projects out of the insertion slot, e.g., in a notebook computer, so that during mobile operation there is a risk that the contact unit will jam in the slot or might even be bent or damaged. This extension has thus far been considered necessary for safely guiding the chip-card into and out of the slot-type insertion channel without the risk of inserting the card improperly--that is, for introducing, retaining, and removing a chip-card.
As the usage of transportable computers (e.g., laptop and notebook computers) continues to increase, there is a technical requirement that a chip-card reader situated in the operating position be completely insertable into the slot in the computer without projecting parts interfering with usage. This becomes important, e.g., when a chip-card must be inserted for personal authorization to use the computer. Although contact elements are known that do not comprise an extension and thus correspond to the PCMCIA standard, these are provided at least partially with closed sides in order to achieve lateral guidance for the chip-card. However, a significant market requirement is that the width of a contact unit also comply exactly with the PCMCIA standard so that even the wall thickness, 1/10mm, for the sides does not deviate substantially from the PCMCIA standard. An additional disadvantage of very thin-walled sides is that the slightest misplacement of the chip-card when it is inserted into the contact unit can damage the card. An additional disadvantage results when the thin sides are deformed and it is then no longer possible to insert the chip-card.
The object of the invention is to further develop a contact unit for a card-shaped carrier element in electronic components such that the contact unit can be completely inserted into a PCMCIA slot in a computer without parts projecting therefrom and the object is furthermore also to ensure that proper insertion is still possible and that there is sufficient mechanical stability and simple manufacture.
This object is achieved in a contact unit of the type cited in the foregoing in that the insertion channel is continuously open over its entire length in the direction the chip-card is inserted and in that the base plate and cover plate are securely attached to each other solely in the region adjacent to the insertion channel in the direction of insertion.
The features in accordance with the invention make it possible to provide a contact unit the length and width of which comply precisely with the PCMCIA standard, e.g., Type II, and which can be inserted in its entirety into the PCMCIA slot of a computer (e.g., a notebook computer) without parts projecting therefrom. The complete insertability precludes any risk of damage, especially during transport, wherein a protective flap can also be provided that closes the PCMCIA slot when the contact unit is inserted. Of course, in this case it is not possible to leave a chip-card in the contact unit since, corresponding to the length of the region adjacent to the insertion channel, it projects from the contact unit when in its inserted position.
In a preferred embodiment of the invention, the connection of base plate and cover plate in the region adjacent to the insertion channel in the direction of insertion is also a swivelling axis relative to which the base plate and cover plate can swivel slightly such that the height of the insertion channel can be changed against the effect of a restoring force. The advantage of this is that when inserted into the insertion channel the chip-cards can be retained clamp-like in the channel. It is particularly advantageous when the height of the insertion channel declines as the distance from the connection increases when there is no chip-card inserted therein. When the chip-card is inserted into the insertion channel, the latter expands and the chip-card is held securely in the channel by means of inherent elastic return deformation. At the same time a high degree of form stability in the contact unit and compensation of production tolerances can be achieved in this manner.
Furthermore, a particular advantage is that the printed circuit board is connected at its end opposing the plug-in strip to a metal strip that is affixed to the printed circuit board in the housing and that comprises flexibly extending tabs that electrically conductively adjoin the metal cover plate. The metal strip in this manner keeps the printed circuit board level in the housing and also provides a grounded transition to the printed circuit board. With regard to this latter, it is necessary that the metal strip is connected to grounded contact surfaces in the printed circuit board. In order to facilitate simple assembly, in accordance with an additional feature of the invention the metal strip is arranged on a plastic profile that is connected to the cover and that constitutes an upper insertion guide for the chip-card. The plastic profile can be provided on its side facing the insertion channel guides for a chip-card and can be joined to the metal strip, e.g., by clamping, adhesive, or locking means.
In accordance with a further advantageous development of the invention, provided in the insertion channel is at least one spring element, the one end of which is securely joined to the cover plate and the other, free end of which can be detachably attached to the base plate. The spring element fulfills a plurality of roles. When no chip-card is inserted, the spring element ensures that the height of the insertion channel remains the same against the action of the restoring force so that the chip-card can be easily introduced. Since the free end of the spring element is detachably attachable to the base plate, the insertion channel is simultaneously protected against outward expansion. This provides the contact unit additional form stability. Introducing the chip-card releases the free end and the spring element is bent in the insertion channel in the direction of the cover plate so that due to this spring-effect the chip-card is subjected to increased pressure which also ensures the contact. Advantageously the spring element is produced integral to the metal strip and when a chip-card is inserted extends to the cover plate through cut-outs in the printed circuit board so that chip-card and metal cover plate are conductively connected to each other, whereby static charging of the chip-card can be prevented. Securing the free end of the spring element on the base plate also makes it possible to achieve a bonding point between cover plate, printed circuit board, and base plate when there is no chip-card inserted. The metal strip and the spring element are cost-effective to produce by means of stamping and bending as strip-type goods and can be joined to the cover plate or to the plastic profile constituting the upper insertion guide in a single step by means of caulking, adhesive, welding, or ultrasound welding.
In order to obtain the compression/tension effect with the spring element, it is useful to embody the spring element in an approximate S-shape and to provide at its free end a claw-shaped extension that engages a mating lock element for securing the spring element. In accordance with an additional feature of the invention, it is advantageous to provide the lock element an undercut in which the claw-shaped extension of the spring element is releasably held. In an advantageous embodiment of the invention it is furthermore suggested that the lock element is embodied in a reinforcing plate made of plastic or metal that is joined to the base plate. While a reinforcing plate made of plastic can be joined to the metal base plate by means of injection molding, a metal reinforcing plate can be joined to the base plate by means of welding or adhesive. Advantageously the lock element is employed as a separate component in the reinforcing plate or as a cut-out in the reinforcing plate that is at least single-layer. In the latter case the undercut in the lock element can be produced by punching or stamping a single-layer reinforcing plate or by the offset arrangement of two reinforcing plates, one above the other and provided with openings. If, however, the lock element comprises a separate component, it is useful to prefabricate this component and press it into an opening in the reinforcing plate.
In accordance with an additional feature of the invention, the base plate at its end opposing the plug-in strip is provided with a plastic profile that functions as a lower insertion guide in order to ensure that the chip-card can be easily inserted. The plastic profile can be provided guides analogous to those for the upper insertion guide.
In an advantageous embodiment of the invention it is furthermore suggested that the base plate and cover plate are each provided at said plug-in strip with plastic holders arranged on the edge for fastening thereto that can be securely joined by means of a plastic bond like adhesive, ultrasound welding, or heat pressing. Base plate and cover plate can be securely joined in this manner. Alternatively, or in addition thereto, in accordance with an additional feature of the invention the base plate and cover plate are congruent and are welded to each other at lateral welded brackets. In this case it is particularly advantageous when the length of the secure joining of base plate and cover plate is approximately 30% of the overall length of the contact unit because this results in high form stability in the contact unit. Finally, it is suggested that an end stop comprising a stop angle is provided for limiting the insertion of the chip-card. Depending on requirements, insertion of the chip-card can also be limited by the lateral welding brackets or by the plastic holders, which are then provided with appropriate rounded stop surfaces.